Fuel cell research has largely been dominated by discussion of possible ways to utilize evermore expensive platinum electrocatalysts. In H2 or alcohol based fuel cells where hydrogen is the ultimate electron source, platinum remains the definitive performer. At the anode, the current state of the art utilizes decorated nanoparticles of Pt/Ru alloy phase supported on high surface area carbon blacks [(Svitlana Pylypenko, 2009)]. It is generally believed that the improved fuel oxidation and enhanced resistance to CO poisoning seen with Pt/Ru is a result of the bi-functionality of the material [(Debra R. Rolison, 1999) (K. Sasaki, 2008)].
Carbon blacks have traditionally been used as the catalytic support for PtRu due to their excellent electronic conductivity and high surface areas ranging from 150 to 1200 m2/g. The outer surface of the most commonly used carbons is graphitic with a low degree of oxidation, while the interior remains amorphous and especially susceptible to corrosion. See, e.g., Borup, R. et al, Chemical Reviews 2007, 107 (10), 3904-3951; and Kinoshita, K., Carbon: Electrochemical and Physicochemical Properties. Wiley: New York, 1988. There are three primary means of failure of carbon as a catalytic support. The first develops from percolation effects in the conductive carbon matrix as the material shifts and its simple morphology is unable to maintain as many points of electrical contact among particles, resulting in ohmic losses. Because carbon does not interact with the catalyst, kinetic losses also occur when platinum particles agglomerate and migrate around and off of the support surface, leading to sintering and loss of catalyst/support contact. Consequently, platinum and ruthenium have been shown to detach from the carbon and migrate across the ion exchange membrane [(Karl J. J. Mayrhofer, 2008) (Wu Bi, 2008) (Hector R. Colon-Mercado, 2005)]. Finally, carbon forms surface oxides which create a hydrophilic interface and lead to flooding of the support, ultimately hindering fuel flow to the catalyst.
Carbon supports do not participate in the catalytic oxidation/reduction reactions and offer low stability, leading to degradation of the fuel cell. Despite this, very few reports have discussed the alternatives to carbon. In some studies, because of their lesser conductivities [(M. Vettraino, 2001) (M. Vettraino M. L., 2000)], small amounts of strongly oxidizing metals have been used [(Brenda L. Garcia, 2007) (Kyung-Won Park, 2007)]. Alternatively, small to moderate weight percents of metal oxides supported on carbon are implemented as pseudo-supports for catalyst [(K. Sasaki, 2008)].